Re: [GnomeMeeting-list] Call to Gnomemeeting from endpoint behind NAT

[Damien Sandras <damien sandras it-optics com>]

Hi,

We are not openphone experts, but I believe that you can configure
openphone to work like gnomemeeting, choosing your ports yourself and
enabling IP Translation + port forwarding.

But if it worked with netmeeting, it means the router of your friend
supports H.323. You can thus disable tunneling and fast start on the
openphone side and call, it should work.


Le ven 16/01/2004 à 18:38, Conrad Beckert a écrit :
> Hi
> 
> can anyone help me with this:
> 
> My gnomemeeting is on an public IP - visible to
> everyone. My partner was on Netmeeting and sits behind
>  a NAT Router he has no control of. (Some DSL Router
> out of the box - so I don'k know if it natively
> supports H323 address translation)
> 
> Netmeeting works - my partner can call me using my
> dyndns. 
> 
> Now I installed openphone on his machine (based on
> OpenH323 - for using Speex codecs) The network is
> still the same.
> 
> Openphone connects and can send images and sound to me
> but I'm invisible and silent on the other side.
> 
> I set up the ports using UDP for RTP/RCTP 5000-5020
> and 30000-30010 to get through my packet filter - so I
> think the packets go through my firewall.
> 
> I analyzed the protocol between Openphone and
> Gnomemeeting on my little internal network (without
> NAT) and it looks like this: (Call initiated from
> Openphone)
> 
> 1. Openphone calls GM on 1720 (sender port is 1085)
> 2. negociations take place between the endpoints (TCP
> and Q.931 packets)
> 
> 3. Gnomemeeting starts sending packets to Openphone
> port 5008 with sender 5000
> 4. Openphone returns using the same ports (happens
> quite a few times - obviously that's the RTP
> audio/video data yet)
> 5. Gnomemeeting starts sending packets to Openphone on
> port 5009 with sender 5001
> 6. Openphone returns using the same ports - obiously
> that's the RTCP data
> 7 later there is a conversation from GM port 5001 to
> Openphone 5009 and another from GM 5003 to 5011 that
> in the same direction that gets answered. 
> 
> My conclusion: I don't know if I'm right as I'm not an
> H323 expert:
> What happened:
> - Openphone calls Gnomemeeting from behind the NAT
> router and gets its answer because the router knows
> where to send the returning packages to.
> - Gnomemeeting starts sending to 5008 - the Nat does't
> know what to do with it and drops the packets.
> - Openphone starts sending and is hence visible.
> 
> I suppose that Netmeeting issues the connections from
> behind the NAT and thus the NAT knows how to handle
> the returning Gnomemeeting packets. (Though I have
> another Netmeeting partner of which I have the same
> phenomenon as with Openphone)
> 
> Can anybody help me:
> - How can I set up the Openphone (or OpenH323
> respectively) to initiate the RTP/RTCP connection and
> get Gnomemeeting to reply its data from/to the same
> ports?
> - Is H323 capable of doing so after all? Perhaps I've
> misinterpreted my observations and all my efforts were
> futile from the beginning.
> - I've read about Master-Slave Determination. Is this
> how to tell both endpoints who should start sending on
> which port? Is there a way to control this to get the
> endpoint behind NAT to start?
> 
> 
> Thank you in advance for help
> Conrad
> 
> 
> 
> 
> 
> =====
> 
> 
> __________________________________________________________________
> 
> Gesendet von Yahoo! Mail - http://mail.yahoo.de
> Mit Yahoo! Suche finden Sie alles: http://suche.yahoo.de
> _______________________________________________
> GnomeMeeting-list mailing list
> GnomeMeeting-list gnome org
> http://mail.gnome.org/mailman/listinfo/gnomemeeting-list
-- 
 _      Damien Sandras
(o-     
//\     It-Optics s.a.
v_/_    GnomeMeeting: http://www.gnomemeeting.org/
        FOSDEM 2004:  http://www.fosdem.org
        H.323 phone:  callto:ils.seconix.com/dsandras seconix com